Re: 2us Interrupt latency's for Linux 2.0.xx

Petko Manolov (petkan@varel.bg)
Wed, 02 Sep 1998 11:49:59 +0000

MOLNAR Ingo wrote:
>
> _external_ interrupts have much higher latencies. (especially as old
> XT-PIC interrupts halt the CPU for a considerable amount of time ... this
> is not the case with IO-APIC and inter-CPU interrupts.)

It's very interesting to me how is profiled IRQ latency
without osciloscope or other hardware. With time stamp register you
can profile only the time spend in IRQ handler. I think the time between
device request and lowering #INTR pin of the CPU can be profiled only
with external HW. Anyway i think this time is constant (for every single
manifacturer).

Petkan

-- 
Petko Manolov, http://www.varel.bg/~petkan


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